Relationship between Resolution Blur and Shot Noise in Line Edge Roughness Formation of Chemically Amplified Resists Used for Extreme-Ultraviolet Lithography

The line edge roughness (LER) of resist patterns is a serious concern in extreme-ultraviolet (EUV) lithography. The resolution blur (caused by secondary electrons) and the shot noise of EUV photons affect LER. In this study, the relationship between resolution blur and shot noise in the LER formation of chemically amplified resists was investigated assuming a virtual sensitization mechanism. The sensitization distance was defined as the distance from the EUV absorption point and the LER of line-and-space patterns with 11 nm half-pitch was calculated by a Monte Carlo method. The relationship between the shot noise limit, the sensitization distance, and the total sensitizer concentration was clarified. In the energy-deficit region, it was feasible to improve the sensitivity by increasing the (apparent) quantum efficiency while maintaining 20% critical dimension (CD) line width roughness (LWR).